Hepatitis A Virus Infections in the United States: Model-Based Estimates and Implications for Childhood Immunization

Abstract

These results suggest a large reservoir of infection in children and that interruption of transmission in children may substantially reduce incidence of hepatitis A overall.

Cost-effectiveness of childhood hepatitis A vaccination in Argentina: a second dose is warranted

“…Four immunization options were assessed: (1) no hepatitis A vaccination; (2) hepatitis A vaccination at age 12 months only; (3) hepatitis A vaccination at ages 12 and 72 months; and (4) hepatitis A vaccination at ages 12 and 18 months. As listed, these interventions are progressively more costly.…”

“…To estimate the number of infections from reported cases, two assumptions were made: (1) 100% of reported cases had overt illness; and (2) the proportions of infected individuals with overt illness are as follows: less than 5 years old, 7.0%; 5 to 9 years old, 37.0%; 10 to 14 years old, 71.0%; 15 to 49 years old, 75.7%; and 50 years and older, 86.0% (4,17). Under these assumptions, peak infection rates occurred between ages 2 and 4 years in each region (Table 1).…”

“…A United States model of intrahousehold transmission (33) was adapted to Argentina to account for larger household sizes (34), higher rates of hepatitis A immunity (10,(26)(27)(28)(29)(30)(31)(32), and more recent data on agespecific probabilities that hepatitis A infections will cause overt disease (4). The model predicts the number of secondary cases resulting from personal contact with individuals infected with hepatitis A based on household size, age distribution, and age-specific probabilities of having hepatitis A immunity.…”

“…Persons infected after early childhood often experience extended morbidity (4,5). Jaundice, fever, malaise, anorexia, nausea, and abdominal discomfort are common.…”

“…The concern with one-dose vaccination is that long-term immunity will not be conveyed, and the average age of acquisition may be shifted to adulthood. Since hepatitis A is more severe in older individuals (4,5), an even greater disease burden may result.…”